/*
* Copyright 2002-2016 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.integration.scripting.jsr223;
import javax.script.Bindings;
import javax.script.ScriptEngine;
import org.springframework.integration.scripting.ScriptExecutor;
/**
* A {@link ScriptExecutor} that implements special handling required for Python to
* emulate behavior similar to other JSR223 scripting languages.
* <p>
* Script evaluation using the Jython implementation results in a <code>null</code> return
* value for normal variable expressions such as <code>x=2</code>. As a work around, it is
* necessary to get the value of 'x' explicitly following the script evaluation. This
* class performs simple parsing on the last line of the script to obtain the variable
* name, if any, and return its value.
*
* @author David Turanski
* @author Gary Russell
* @since 2.1
*
*/
public class PythonScriptExecutor extends AbstractScriptExecutor {
public PythonScriptExecutor() {
super("python");
}
@Override
protected Object postProcess(Object result, ScriptEngine scriptEngine, String script, Bindings bindings) {
Object newResult = result;
if (newResult == null) {
String returnVariableName = PythonVariableParser.parseReturnVariable(script);
if (bindings != null) {
newResult = bindings.get(returnVariableName);
}
if (newResult == null) {
newResult = scriptEngine.get(returnVariableName);
}
}
return newResult;
}
public static class PythonVariableParser {
public static String parseReturnVariable(String script) {
String[] lines = script.trim().split("\n");
String lastLine = lines[lines.length - 1];
String[] tokens = lastLine.split("=");
return tokens[0].trim();
}
}
}